Landing bearing and magnetic bearing assembly

Abstract

A landing bearing for use in a magnetic bearing assembly is provided. The landing bearing includes a first landing surface configured to be mounted on a shaft and a bushing having a second landing surface configured to be mounted in a housing or in a stator coaxially with the landing sleeve. The second landing surface is arranged so as to face the first landing surface. It is proposed that at least one of the first landing surface and the second landing surface is provided with at least one recess for receiving lubricant.

The invention claimed is: 
     
       1. A landing bearing for use in a magnetic bearing assembly, the landing bearing comprising:
 a. a first landing surface; 
 b. a second landing surface, the second landing surface facing the first landing surface; 
 c. the first landing surface is provided with a plurality of recesses for receiving lubricant, wherein each of the plurality of recesses are isolated from the others such that none of the plurality of recesses connect to another one of the plurality of recesses; 
 d. a porous structure layer disposed over the first landing surface, wherein a side of the porous structure layer opposite the first landing surface forms a contact surface for initially contacting the second landing surface during use; and 
 e. lubricant disposed within the porous structure layer and within the plurality of recesses such that lubricant in the plurality of recesses is capable of travelling from the plurality of recesses and then travelling through the porous structure layer in a circumferential direction prior to reaching the contact surface. 
 
     
     
       2. The landing bearing according to  claim 1 , further comprising a landing sleeve configured to be mounted on a shaft, wherein
 the first landing surface is a surface of the landing sleeve. 
 
     
     
       3. The landing bearing according to  claim 2 , further comprising a bushing mounted in a housing or in a stator coaxially with the landing sleeve, wherein
 the second landing surface is a surface of the bushing. 
 
     
     
       4. The landing bearing according to  claim 3 , wherein the second landing surface is also coated with the porous structure layer. 
     
     
       5. The landing bearing according to  claim 1 , wherein the porous structure layer has a pore size of 0.001 to 2 μm, porosity density 1 to 20% and/or layer thickness of 0.5 to 20μm. 
     
     
       6. The landing bearing according to  claim 5 , wherein the porous structure layer provides at least one of Mn-phosphate, Zn-Ca-phosphate and black oxide. 
     
     
       7. The landing bearing according to  claim 6 , wherein each of the plurality of recesses has a depth in a range of 0.25 to 1 mm. 
     
     
       8. The landing bearing according to  claim 7 , wherein each of the plurality of recesses has width in a range of 0.5 to 3 mm. 
     
     
       9. The landing bearing according to  claim 7 , wherein each of the plurality of recesses is formed as one groove out of a plurality of grooves formed as straight lines in parallel or curved lines. 
     
     
       10. The landing bearing according to  claim 7 , wherein a plurality of isolated dimples forms the plurality of recesses. 
     
     
       11. The landing bearing according to  claim 10 , wherein a percentage of a recessed surface area is 5-20% of the total surface area of the first landing surface. 
     
     
       12. The landing bearing according to  claim 1 , wherein a density of a recessed surface area is 5-20% of the total surface area. 
     
     
       13. The landing bearing according to  claim 1 , further comprising a landing sleeve configured to be mounted on a shaft, wherein
 the second landing surface is a surface of the landing sleeve. 
 
     
     
       14. The landing bearing according to  claim 13 , further comprising a bushing mounted in a housing or in a stator coaxially with the landing sleeve, wherein
 the first landing surface is a surface of the bushing. 
 
     
     
       15. A magnetic bearing assembly including at least one landing bearing, the at least one landing bearing comprising:
 a. a first landing surface; 
 b. a second landing surface, the second landing surface facing the first landing surface; 
 c. the first landing surface is provided with a plurality of recesses for receiving lubricant, wherein each of the plurality of recesses are isolated from the others such that none of the plurality of recesses connect to another one of the plurality of recesses; 
 d. a porous structure layer disposed over the first landing surface, wherein a side of the porous structure layer opposite the first landing surface forms a contact surface for initially contacting the second landing surface during use; and 
 e. lubricant disposed within the porous structure layer and within the plurality of recesses such that lubricant in the plurality of recesses is capable of travelling from the plurality of recesses and then travelling through the porous structure layer in a circumferential direction prior to reaching the contact surface.